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SFE general

SFE general: Stacking fault energy, general
Definition:Generalized stacking fault energy
Explanation:Rice proposed an important solid state parameter, unstable stacking fault energy (SFE) ,γus, as the controlling parameter for dislocation emission at a crack tip under shear loading. Consider the process by which an infinite crystal is cut in half along a plane, and the upper half is sheared with respect to the lower half by a displacement vector f and let Φ(f) be the energy per unit area on the slip plane associated with this displacement. The energy surface Φ(f) obtained as a function of the generalized displacement vector f is called the generalized stacking fault energy (GSFE) surface [1]. This energy-displacement curve is known as the GSFE curve. Rice has employed the extreme points of the GSFE curve to study dislocation nucleation at a crack tip (see unstable SFE). The GSF has received considerable attention due to their close relation to the mechanical properties of solids. Rice’s unstable SFE, γus is the lowest energy barrier in the γ surface that has to be surmounted during the shearing process that takes a crystal from an ideal configuration to another equivalent one. Fig. 1 shows the GSFE curve for the <112> direction in an fcc crystal. The points C, C’ and A correspond to the lattice structures shown above [2].
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Fig. 1. The GSF energy curve for the <112> direction in an FCC crystal [2].
SFB-Link:In the issues of dislocation nucleation in a crystal, it is desirable to know the shape of the entire GSFE curve to use it in a criterion for nucleation.
References:[1] Y.Juan, E.Kaxiras. Generalized stacking fault energy surface and dislocatioini properties of silicon: a first-principles theoretical study[J]. Philosophical magazine A, 1996, 74: 1367-1384.
[2] J.A.Zimmerman, H.Gao, F.F.Abraham. Generalized stacking fault energies for embedded atom FCC metals[J]. Modelling simulation in materials science and engineering, 2000, 8: 103-115.